WIP: Mass DLA import

This is a first attempt at completely fixing https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=859122

This was done with:

rsync -vPa master.debian.org:/home/debian/lists/debian-lts-announce .
cd debian-lts-announce
xzcat *.xz > ../giant.mbox
cd ..
mbox2maildir giant.mbox debian-lts-announce.d
for mail in debian-lts-announce.d/new/*; do
  ./parse-dla.pl $mail;
done

This adds around 2400 DLAs missing from the website. Some DLAs will still be missing, more notoriously the ones from the mailing list problem documented in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=913426.

But there are also other issues: the graphite2 regression DLA documented in this post has never been added to data/DLA/list so it has never had a real DLA identifier. same for the DLA-1263 duplicate. Finally, in the first months of the mailing list, DLA identifiers were not consistently used so those were simply ignored.

This should otherwise be fairly thorough. It will obviously need to catchup with whatever is going on now, but it's up to date with the current state of the security tracker, which has DLA-1610 as the latest identifier.

One thing that is missing is adding the DLAs to the index: for example the recent patches (!41 (merged) and !42 (merged)) didn't add an entry here:

https://www-staging.debian.org/security/2018/

So we need to figure that out before merging it. Probably.